1. Field of the Invention
This invention relates to a magneto-optical disk memory using a magnetic thin film recording medium wherein recorded information can be detected by use of a magneto-optical effect such as a magneto-optical Kerr effect or a Faraday effect.
2. Description of the Prior Art
There have heretofore been known magneto-optical recording media wherein information is recorded by changing a magnetic field and the recorded information is detected on the basis of a magneto-optical effect such as a magneto-optical Kerr effect or the Faraday effect.
The magneto-optical recording media are fabricated by overlaying a thin film of an amorphous magnetic alloy such as Gd-Co, Gd-Fe, Tb-Fe, Gd-Tb-Fe, or Tb-Fe-Co, on a non-flexible hard substrate made of glass, polymethyl methacrylate (PMMA), or polycarbonate (PC). The hard disks thus fabricated are considered excellent as high-density recording media wherein the recorded information is erasable.
However, when the magneto-optical disk memories are fabricated, the substrates of glass or the like formed in advance in a final shape must be cleaned and thin films must be overlaid on the substrates one by one by use of a batch type sputtering apparatus or a deposition apparatus. Therefore, the conventional magneto-optical disk memories are not suitable for mass production. Particularly, when a plurality of thin layers such as a substrate treatment layer, a reflecting layer, a dielectric layer, and a protective layer are overlaid on the substrate or when the thin layer is grooved for facilitating tracking control or addressing, the productivity of the magneto-optical disk memory is low, and the manufacturing cost becomes high.